Fabrication and electrochemical performance of Si-based porous electrodes for thin-film lithium-ion batteries

The use of porous silicon (Si)-based thin-film electrodes is essential for developing high-performance thin-film lithium-ion batteries with high energy density and power density. However, it is still challenging to fabricate porous Si film economically and environmental harmlessly. Here, we report a facile synthesis method to obtain high-performance porous Si/TiO2 thin film electrode through heat treating a physical vapor deposited Si/TiO2 multilayer film. As the representative, the STO350 sample that is obtained via a heat treatment of the as-deposited Si/TiO2 multilayer film at 350°C for 2 h in Ar atmosphere exhibits a specific capacity as high as 1504 mAh g−1 at a current density of 2.5 A g−1 after 1000 cycles. The capacity change is only 0.027% per cycle from the 30th to 1000th cycle. Even at 5 A g−1, it can still output a specific capacity of 1120 mAh g−1. Our study also suggests that amorphous TiO2 is more beneficial for the Li-ions transport kinetics than anatase TiO2 in the Si/TiO2 thin film electrode.